https://blog.wongcw.com/2018/09/28/linux%e7%b3%bb%e7%b5%b1%e4%b8%8b%e5%a6%82%e4%bd%95%e6%9f%a5%e7%9c%8bcpu%e5%9e%8b%e8%99%9f%e3%80%81%e6%a0%b8%e5%bf%83%e6%95%b8%e9%87%8f%e3%80%81%e9%a0%bb%e7%8e%87%e5%92%8c%e6%ba%ab%e5%ba%a6%ef%bc%9f/